Recovery and regeneration of oxo process catalysts



Feb. 8, 1966 H. R. NULL ETAL 3,234,145

RECOVERY AND REGENERATION OF OXO PROCESS CATALYSTS 4 Sheets-Sheet l Filed Jan. 18, 1963 |IIT Unull Feb 8, 1966 H. R. NULL ETAL RECOVERY AND REGENERATION OF OXO PROCESS CATALYSTS Filed Jan. 18,

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Feb. 8, 1966 H. R. NULL ETAL RECOVERY AND REGENERATION OF OXO PROCESS CATALYSTS Filed Jan. 18, 1965 4 Sheets-Sheet 4 United States Patent() 3,234,146 RECOVERY AND REGENERA'IION 0F 0X0 PROCESS CATALYSTS Harold R. Null, Florissant, and Leon E. Bowe, Glendale, Mo., assignors to Monsanto Company, a corporation of Delaware Filed Jan. 18, 1963, Ser. No. 252,500 8 Claims. (Cl. 252-413) The present invention relates to an improvement in the oxo process, specifically with respect to the recovery of the catalyst which-is employed, as well as the regeneration of the catalyst for recycling. lt is an objectof the invention to provide a method for the recovery of the catalytic components, particularly for the purpose of employing `such components in further catalytic reactions such as condensation or for the recycling of such components in the basic oxo process.

It is known in the art that the carbonylation of olenic compounds with carbon monoxide and hydrogen, catalyzed `by cobalt involves the formation of a cobalt carbonyl. It has been recognized that the essential catalytic element in the carbonylation reaction is cobalt carbonyl or cobalt hydrocarbonyl regardless of theinitial source of the cobalt. The further conduct ofthe reaction in the addition of carbon monoxide and hydrogen to anolefin, such' as propylene, then results in the formation of oxygen-.containing organic compounds, specifically aldehydes, such as nbutyraldehyde and isobutyraldehyde. It is sometimes desired to obtain higher-molecular-weight c ompounds such as eight-carbon atom aldols by condensation of the said four-carbon-aldehydes.- Itis desirable to employ the same catalyst for the preliminary carbonyla-tion as well as the second step of -condensation as described above. However, it has heretofore been found that the metal carbonyls which :catalyze the carbonylation reaction are impractical or ineffective for the catalysis of the condensation reac- Ition. In addition, carbonyls are poisons with respect to hydrogenating catalysts, such as Raney nickel. This factor becomes important since hydrogenation follows condensation in the processing of the products of the` present invention.

The catalyst contemplated by the present invention is based upon a .combination of two components. The first component is an oxide, hydroxide, salt or carbonyl of cobalt. Inorganic salts such as the nitrate, carbonate, chloride, or sulfate may be employed. However, it is preferred that the said salt be a salt of an organic acid, still more preferably having from 4 to 20 carbon atoms. Examples of the acid moiety in combination with the said metals include the stearate, alpha-ethylcaproate, also known .as Z-ethylhexoate, dodecanoate, naphthenate, tallate (acids from tall oil), phthalate, benzoate, maleate, adipate and the like. The term salt as used herein also includes` other organic compounds such as cobalt acetylacetonate.

The second component of the combination catalyst is an organic manganese salt. It is preferred that the said salt be a carboxylate which is soluble in the aldehyde product resulting from the oxonation. Preferred examples of such manganese carboxylates include the stearate, alpha-ethylcaproate, dodecanoate, naphthenate, tallate and the like.

The combination catalyst may be dissolved or dispersed in the reaction product or in a solvent such as benzene or other hydrocarbons, or ethers such as diethyl ether. The present reaction may also be conducted in the presence of` free organic acids, set forth above, which may be present in a concentration of 0.01% to 10% by weight, relative to the said salts described above.

The oxo process of the present invention involving a combination method for conducting an oxonation reaction Patented Fein. 8, 1966 together and concomitantly with a condensation reaction using a cobalt-manganese catalyst may be carried out in a number of ways. The simplest method of operation is to employ a batch type of reactor to which the desired proportions of olefin, carbon monoxide and hydrogen are charged together with the aforesaid combination catalyst. The entire charge in this method is placed in an autoclave or other type of batch vessel. The charge is then heated to the desired temperature for oxonation followed by cooling or continued processing such as at a somewhat higher temperature in order -to complete the condensation of the specific aldehydes with the production of a dehydrated aldol. The dehydrated aldols produced by the above methods may be used as intermediates in various processes, but are more commonly hydrogenated to obtain alcohols useful as solvents or plasticizer intermediates.

The present catalyst recovery process provides a means for the substantially compl-ete recovery of the cobalt and manganese values which are present in the catalyst either at the conclusion of the condensation and hydrogenation steps, or if desired, the process may be applied directly after the primary carbonylation reaction in which the olefins are transformed to aldehydes. In the latter circumstance in which the catalyst exists substantially completely as cobalt carbonyl and (manganese carbonyl when the managanese is employed together with a cobalt), a partial recovery of the metal values may be accomplished by merely releasing the pressure upon the system whereupon some of the metal carbonyls are decomposed with the evolution of carbon monoxide and the deposition of the metal e.g., the cobalt and manganese. The remaining liquid is then passed directly to the present recovery process.

The recovery system is also applicable to the modification of the oxo process in which the same metal values pass through the entire reaction stream of carbonylation, condensation and hydrogenation. Essentially the present process comprises an acid decomposition of the metal salt and carbonyl components followed by selective extraction of the anionic and cationic components.

The unitary oxo process in which a combination catalyst such as the cobalt and manganese components is used for the combination reactions of carbonylation, condensation and hydrogenation is generally conducted by charging the original catalytic metal components as organic salts such as cobalt 2-ethylhexoate, manganese 2- ethylhexoate, or the corresponding stearates or tallates (the organic acids found in tall oil). An excess of the organic acid, such as from 0.01% to 10% over the stoichiometric, may also be charged with the initial catalytic components, or may be added to the final spent catalyst stream or even the complete oxo reactor effluent in order to have present the organic acid anions for the recovery of the cationic metal components (including metals present as carbonyls). Thus, the present recovery process in segregating the metal components by acid extraction, followed by saponification with an alkaline material, including caustic substances such as sodium hydroxide, potassium hydroxide as well as alkaline earth compounds of the alkali and alkaline earth elements, permits the recovery also of the anionic or acid radicals eg., the Z-ethylhexoate, stearate land tallate radicals as discussed above, as corresponding to the originally charging organic metal salts. For example, potassium Z-ethylhexoate is the intermediate product when employing potassium hydroxide added to the stream containing Z-ethylhexoate esters or other combined and free forms of the Z-ethylhexoate esters o1' other combined and free forms of the Z-ethylhexoate radicals.

The present recovery process embraces the following essential steps. The mineral acid is used to contact the catalytic source such as a metal concentrate in liquid,`

slurry or solid form. The source may also be the kcrude product of the Voxonation reactor, either after the carbonylation steps or after the condensation or hydrogenation steps. may employ sulfuric, phosphoric, nitric or hydrochloric acids of from 1% to 75% acid strength and with from` 100% to 200% of the stoichiometric proportion of acid relative to the metal to be recovered.

The above step of acid lcontacting may be carried out at room temperature or atfmoderate temperatures eg., up to 150 at which the organic products yare available from the oxo process. In the step lwhich consists of treating the crude oxo eliiuent, or a catalyst concentrate avail able from other recovery systems, with a mineral acid, the vtemperature can range from 20 C. to 150 C., and any contact time above one minute. These ranges are also applicable to the optional washing step which fol-V lows the acid contacting.

After the mineral acid contacting there is a phase separation of the aqueous or acid layer containing the metal salts, c g., cobalt sulfate and manganese sulfateV when employing sulfuric acid. The supernatant organic phase contains the organicnacid corresponding to the original metal salts eg., the stearic or Z-ethylhexoic acid as well iV as any excess organic acid which may have been introduced or formed during the course of the process.

This organic phase may optionally be washed ywith water or weak acid to complete the removal of metal. components as the sulfate or other acid salt.` Such wash-- ings are combined-with the aqueous phase from the first step.

The first stage of the recovery system e.g., the acid contacting of the crude catalyst source is conducted in any suitable, acid resistant material such as an autoclave or mixing vessel. Mixing means are generally desirable in order to promote rapid contacting ofthe acid, for example 35% nitric acid, and the catalyst either in solid,

slurry or liquid form.

The organic phase after the acid treatment is subjected to saponification conditions such as with a 50% solution of sodium hydroxide, although solutions ofy from to 60% of NaOH or KOH may be employed. The caustic is most conveniently used at from 10% to 150% by weight-relative to the organic phase. After the completion of the saponication step, a phase separation is again employed to remove the aqueous excess caustic from the supernatant organic phase. The organic phase is then separated from the caustic, although this step may be combined with water washing such as in a eountercur.- rent extractor or scrubber wherein the organic phase consisting of the alcohols and the dehydrated aldols of the original aldehydes are washed free of the alkali salts such as the sodium salts resulting from saponiiication with sodium hydroxide. The aqueous extracts are then employed in further steps of the ,present process while the organic phase is subjected to refining operations such as distillation.

Saponication can be satisfactorily effected at a temperature between 70 C. and 100 C., or preferably' from 90 C. to 100 C. A contacttime preferably greater than 10 minutes such as from l0 to 30 minutes is used. When a water Wash of the organic product is used, the temperature of such step is not critical although a desirable range is from 40 C. to 100 C. The catalyst reforming step conducted with alcohol of from 2 to 20 carbon atoms` as the extraction medium depends Vfor its critical conditions upon the degree of agitation and contacting which is employed such as in a countercurrent tower operation or agitation in one zone followed by phase separation in another zone in the regeneration is accordinglyfeiective- Such mineral acid contacting, for example',

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presence of acid at this stage, the pH should desirably be maintained in the range of from 7 to 9in1the catalyst reformation stage.

The aqueous streamV from saponitication, containingA the; sodium salts of the organic acids, and the aqueous solution of nitrates from themineral acid decobalting are then preferably.'V contacted in thefpresencezofa heavy alcohol, eg., an alcohol of from 6 to 20 carbon atoms such as the alcohol product in the. oxol process Z-'ethylhexanol or dodecanol. In this step the cobalt and `manganese contentare Ireconverted to the salt of theorganic acidwhile the sodium or' potassium is removed as the original salt f e.g., sodium sulfate, sodium nitrate, etc. sential, it spreerable-to-maintain the ,pH Vduring such contacting in the range of from.7 to.9 since it hasbecn Vfound that such pH control reduces the yamount of cobalt' and manganese salts of the iorganic acid which re-l ture of the mixture in order to complete the! extraction of i the organic metal salts forrecovery ofthe catalytic components, and in order: to provide a recycle catalyst where desired.

The following examples illustrate of the present'invention.`

EXAMPLE 1 specific embodiments While not esf The catalyst recovery system is applied to an oxo unit charging propylene as the; olelin. The reactorIis operated i to obtain condensation and hydrogenatio'n with the cobaltmanganesecatalyst, so that thee-product distribution as r shown in FIGURE l is ypredominantly n-butanol'and 2- The crude product flows at the rate of ethylhexanol.

230.9 lbs. from the oxonation reactor to. the; presentpuril cation system. This stream consists primarily of alcohols with minor proportions of organic'impurities such as estera-and contains the catalyst metals, cobaltand manganese, -as compounds in solution or slurry form; the'` stream is introducedV into a vvesselfwhere it is contacted with'20.1 lbs. of 35 wt. percentnitric acid. .By means of agitation for about 10min'utes at a .temperatureof about t 50 C., the metal compounds react to give water solubte nitrates.`

The Vmixture is then separated into two phases; the or-. garlic phase is pumped to another vessel where it is Washed f' forl0 minutes at about the same temperature yof 50C.

with water or Weak nitric acid` (on the order. of `5% by weight). With thisstep, the remaining metal nitratesV are removed with the aqueous phase andcornbined with the aqueous phase from the first acidV treatment. The organici phase is a then fed to a well-stirred saponiiication reactor Where it is; contacted with"50% (wt.) aqueous sodium hydroxide at atmospheric retiux (approximately v104 C.)

for one hour. This treatment of the organic phase conf verts all esters to the `alcohol' and sodium -salt of theVv acid. The .aqueous phase containingV 30% caustic is in 1 large part recycled back to the saponiiication for re-use.

The organic phase from saponiiication is cooled. to

607 C. and is then fed to a countercurrent extractor Where it is washed free of the sodiumysalts withpwater. Then the organic effluent goes to a distillation train whereit 1s yfurther refined-as product alcohol.`

The aqueous stream containingthe sodium salts and t the previously described aqueous streamcontaining the metal nitrates are mixed .and contacted in the presence of Z-ethylhexanol 'as a representative heavy alcohol. With agitation, andV pH control between 7 and 9, E(this may be'.

regulated bythe addition of a small amount of=nitric acid). The cobalt andV manganese are converted to the.;` salt of the organic acid with residence` time of vaboutf30 mmutes, and the sodium contentV becomes; sodium nitrate whichremains insolution due to its high solubility in Y water; Mostlof'the cobalt and-manganese content are removed as the organic salts, e.g., cobalt and manganese 2ethylhexoate, in the alcohol solution and are ready for recycle. However, in certain cases, some of the cobalt and manganese salts ofthe organic acid remain in colloidal suspension in the aqueous phase and are then fed to a vessel where the aqueous phase is reuxed in the presence of a heavy alcohol such as 2-ethylhexanol- Under these conditions the colloidal suspension is coagulated, and the cobalt and manganese salts dissolve in the heavy alcohol in which it is recycled back to the reactor. Ten minutes residence time and violent boiling is sucient to coagulate the colloid. The aqueous phase may be discarded or treated further for recovery of dissolved organic materials. With this process 99% of. the catalyst metals are recovered.

EXAMPLE 2 The procedure employed here is identical to the preceding example except that a different mineral acid is employed, as shown in FIGURE 2. Sulfuric acid is used here in the proportion of about 19.37 lbs. of sulfuric acid of 29.6 (wt. percent) strength, relative to 230.9 lbs. of crude organic alcohols. a pH between 7 and 9. With this process approximately 99% of the catalyst metals are recovered.

EXAMPLE 3 The procedure employed here is identical to that described in Example 1 with the replacement of nitric acid by a different mineral acid as shown in FIGURE 3. Phosphoric acid is used here in the proportion of about 17.46 lbs. of phosphoric acid of 22% (wt.) strength, relative to 230.9 lbs. of crude organic alcohols. The final aqueous efuent has a pH between 7 and 9. With this process approximately 99% of the catalyst metals are recovered.

EXAMPLE 4 The procedure employed here is identical to that described in Example l with the replacement of nitric acid by a diierent mineral acid as shown in FIGURE 4. Hydrochloric acid is used here in the proportion of about 12.15 lbs. of hydrochloric acid yof 35% weight strength, relative to the 230.9 lbs. of crude organic alcohols. rIhe nal aqueous eiuent has a pH between 7 and 9. With this process approximately 99% of the catalyst metals are recovered.

The drawings of the present invention illustrate specific embodiments of the use of various acids in carrying out the process of the present invention. In the drawings, FIGURE 1 shows the use of nitric acid, FIGURE 2 shows the use of sulfuric acid, FIGURE 3 shows the use of phosphoric acid, while FIGURE 4 shows the use of hydrochloric acid.

The previously described examples are illustrations of a few of the many modifications and variations of the invention as hereinbefore set forth. Other variations may be made without departing from the spirit and scope of the invention.

In the step which consists of treating the crude oxo efuent with a mineral acid the temperature can range from 20-150 C. and any contact time above l minute. These ranges are also applicable to the optimal work step which follows immediately after the acid contact.

Saponiication can be satisfactorily effected at a temperature between 70-100 C. with any contact time of a length greater than minutes being used. The temperature of the extraction which follows the saponication can also be adjusted with the most desirable limits being from 40-1 00 C.

The catalyst reforming step also has regulative variable of temperature and time. This regeneration can best be effected with the use of 0-l00 C. as the allowable temperature range and a contact time of greater than 5 minutes. Critically, the pH must be maintained in the range of from 7 to 9 at this point.

The nal aqueousv effluent` has.

Other modifications will be apparent to those skilled in the art; therefore, only such limitations should be imposed as are indicated in the appended claims.

What is claimed is:

1. Process for the recovery of catalytic metal components as organic metal salts in an oxo process, which comprises contacting a mixture of organic compounds having present in at least partially soluble form therein, catalytic metal components existing as compounds, and organic acid radicals in combined form, which comprises contacting the said mixture with an aqueous mineral acid to extract catalytic metal salts corresponding to the said mineral acid, separating the said metal salts in aqueous solution from the organic components of the aforesaid mixture, thereafter treating the said organic compounds containing the aforesaid organic acid radicals in combined form, with an alkaline compound selected from the group consisting of alkali and alkaline earth metal hydroxides to form the alkaline organic salts corresponding to the organic acid radicals present, extracting the said alkaline organic salts from the said organic compounds, and thereafter reacting the aforesaid mineral acid salts containing the catalytic metal salts with the extract containing the alkaline organic salts to form organicl salts of the said catalytic metals, and contacting the said organic salts with an alcohol having from 2 to 20 carbon atoms, and separating from the said solution an alcohol extract containing the recovered catalytic metals as organic salts.

2. Process for the recovery of catalytic metal components as organic metal salts in an oxo process, which comprises contacting a mixture of alcohols having present in at least partially soluble form therein, catalytic metal components existing at least in part as carbonyl and carbonylate as compounds, together with organic acid radicals in combined tform, which comprises contacting the said mixture with an aqueous mineral acid to extract catalytic metal salts corresponding to the said mineral acid, separating the said metal salts in aqueous solution from the alcohol components of the aforesaid mixture, thereafter treating the said alcohols containing the aforesaid organic 'acid radicals in combined form, .with an alkaline compound selected from the group consisting of alkali and alkaline earth metal hydroxides to form the alkaline -organic salts corresponding to the organic acid radicals present, extracting the said alkaline organic salts from the said organ-ic compounds, and thereafter reacting the aforesaid mineral acid salts containing the catalytic metal salts with the extract containing the alkaline organic salts to form organic salts of the said catalytic metals, and contacting the said organic salts with an alcohol having from 2 to 20 carb-on atoms, and separating from the said solution containing the said solution an alcohol extract containing the recovered catalytic metals as organic salts.

3. Process for the recovery of catalytic metal components in an oxo process in which at least one member of the class consisting of cobalt land manganese organic acid salts having from 2 to 2O carbon atoms are contacted with an olefin having from 2 to 20 carbon atoms in the presence of carbon monoxide and hydrogen, and in which the oxo reactor products contain dissolved catalytic metal components and combined forms of organic acid radicals, the improvement which comprises contacting the said organic oxo products with an aqueous mineral acid to form metal salts corresponding to the said mineral acid, separa-ting the said metal salts in aqueous solution from the organic phase of the said oxo products, thereafter treating the said organic oxo products with an aqueous solution of an alkaline compound selected from the group consisting of alkali and alkaline earth metal hydroxides to form a solution of the alkaline organic salts corresponding to the organic acid radicals, separating the said alkaline salt from the said organic oxo products, and thereafter combining the aforesaid `aqueous solution of mineral acid salts containing the catalytic metal salts, with the aqueous solution containing bined solutions with a heavy `alcohol having from 2 to2() carbon atoms, and separating from the said mixture van alcohol extract containing the recovered catalytic metals as' organic salts.

4. The kkprocess of claim 1 wherein said mineral acid is nitric acid.

5. The .process of claim 1 wherein said mineral acid is sulfuric acid.

6. The process ofl claim 1 wherein said mineralfacid is phosphoric acid.

7. The process of claim 1 wherein said mineral acid is hydrochloric acid.

8. In a process for the recovery of cobalt and man.- ganese catalytic components in an oxo process in which at least one member of the class consisting of cobalt and manganese organic acid salts having from 2 to 20 carbon atoms are contacted with an olefin having from 2 to 20 carbon atoms in the presence of carbon monoxide and hydrogen and in which the loxo reactor products contain,

dissolved cobalt and manganese catalytic components and organic acidrradicals, the improvement which comprises contacting the said acid oxo reactor products with aqueous nitric acid to extract metal nitrate salts, separating the said metal nitrate salts ini-aqueous solution from the organic phase ofthe said oxo reactor products, thereaftertreating, the said organicV reactor products with aqueoussodium o hydroxide to form a solution of the sodium organic salts f .corresponding to the organic acid radicals present, extracting the said sodium organic ,salt from the said organic reactor euent, and thereafter combining the. aforesaid cobalt and manganese nitrate salts with the aqueous solution containing the sodiumforganic salts, and contacting l said combined components lwith- Z-eJzhylhe'xanol, and i separating from thelsaid mixture a 2-ethylhexanol extract containing the recoveredA cobalt and manganese catalytic metals asorganic salts.

References Cited by the Examiner UNITED STATES PATENTS 2,638,487 5/1953 Russumerai. 26o-604Y FOREIGN PATENTS r 731,389 6/1955 GreatBrirain.

1,089,983 10/1954 France.

ToBrAs E; LEvoW, Primary Exrmir'rer. r

SAMUEL H. BLECH, Examiner. 

1. PROCESS FOR THE RECOVERY OF CATALYTIC METAL COMPONENTS AS ORGANIC METAL SALTS IN AN OXO PROCESS, WHICH COMPRISES CONTACTING A MIXTURE OF ORGANIC COMPOUNDS HAVING PRESENT IN AT LEAST PARTIALLY SOLUBLE FORM THEREIN, CATALYTIC METAL COMPONENTS EXISTING AS COMPOUNDS, AND ORGANIC ACID RADICALS IN COMBINED FORM, WHICH COMPRISES CONTACTING THE SAID MIXTURE WITH AN AQUEOUS MINERAL ACID TO EXTRACT CATALYTIC METAL SALTS CORRESPONDING TO THE SAID MINERAL ACID, SEPARATING THE SAID METAL SALTS IN AQUEOUS SOLUTION FROM THE ORGANIC COMPONENTS OF THE AFORESAID MIXTURE, THEREAFTER TREATING THE SAID ORGANIC COMPOUNDS CONTAINING THE AFORESAID ORGANIC ACID RADICALS IN COMBINED FORM, WITH AN ALKALINE COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METAL HYDROXIDES TO FORM THE ALKALINE ORGANIC SALTS CORRESPONDING TO THE ORGANIC ACID RADICALS PRESENT, EXTRACTING THE SAID ALKALINE ORGANIC SALTS FROM THE SAID ORGANIC COMPOUNDS, AND THEREAFTER REACTING THE AFORESAID MINERAL ACID SALTS CONTAINING THE CATALYTIC METAL SALTS WITH THE EXTRACT CONTAINING THE ALKALINE ORGANIC SALTS TO FORM ORGANIC SALTS OF THE SAID CATALYTIC METALS, AND CONTACTING THE SAID ORGANIC SALTS WITH AN ALCOHOL HAVING FROM 2 TO 20 CARBON ATOMS, AND SEPARATING FROM THE SAID SOLUTION AN ALCOHOL EXTRACT CONTAINING THE RECOVERED CATALYTIC METALS AS ORGANIC SALTS. 